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Sleeping with a fan on could leave you with a hacking cough, chest pain and agonising muscle aches, a doctor has warned.
According to US-based medic Dr Naheed Ali, running the cooling device all night puts 'hidden stress' on the body, including leaving the throat and airways irritated, and restricting blood flow to the muscles.
The health risks may be even more significant for those with severe allergies and asthma, as the airflow whips up particles of dust and dirt, which are then inhaled into the lungs.
'People with asthma allergies often wake with extra chest tightness after a night with the fan on,' Dr Ali said.
His warning comes as the UK is set to experience a heatwave, with temperatures predicted to reach up to 30°C in some areas of the UK by Thursday, the Met Office reports.
Many will no doubt be reaching for the devices to aid sleep, as studies show the optimum room temperature for a restful night is between 16°C and 18°C.
' The steady airflow of the fan can leave the nasal passages and throat uncomfortably dry by morning,' Dr Ali told LADbible .
The arid atmosphere aggravates the respiratory passages, leading to an accumulation of mucus in the nasal cavity and sinus areas, as well as phlegm in the throat.
Dr Ali stated: "Thicker mucus forms when the airway lacks moisture, potentially trapping allergens and irritants near delicate tissues."
'Over time, this may trigger coughing, a scratchy voice, or clogged sinuses that linger throughout the day'.
For individuals with allergies: 'Small particles of lint, dander, and pollen remain airborne and can penetrate further into your respiratory tract during sleep.'
Running a fan while sleeping might also lead to muscular issues.
Dr Ali mentioned, "Exposure to cool air on muscles and joints for seven or eight hours may lead to a slight decrease in tissue temperature."
The cold causes muscle tightening as a protective response, and this stiffness might continue until a warming shower or light stretches improve circulation back to normal.
However, Dr Ali said, you don't necessarily have to turn the fan off to avoid all side effects.
He proposed setting a timer to restrict usage duration, increasing the frequency of laundry for linens to minimize floating dust particles, and directing the fan so it doesn’t blow towards the bed.
If the sole method to maintain a comfortable room is through using a fan, set it on a timer to turn off after completing your initial sleep cycle of about ninety minutes.
'Point the air flow towards a distant wall instead of directly at the bed, and place a glass of water next to your nightstand so you can drink from it if your mouth becomes dry.'
He stated: "These minor changes enable the fan to lower the temperature of the room throughout the night without causing additional unease in the airways or joints."
The NHS suggests that the most effective method to deal with hot weather is to maintain cooler indoor environments. You can accomplish this by shutting your windows during daylight hours and then opening them up at nighttime when the external temperatures have decreased.
This follows the Met Office issuing a warning about an unusually early heatwave that might set records later this week.
Pollen levels are anticipated to remain 'very high' across most of southern England and Wales.
Individuals afflicted with hay fever are recommended to stay inside as much as they can to prevent allergens from entering their eyes, face, and hair, according to the medical charity Allergy.
They should also make sure to bathe and shampoo their hair frequently, and change the outer layer of clothes upon entering the home to prevent dispersing pollen inside.
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